Composition and method for removal of carbonylsulfide from acid gas containing same

Abstract

Novel solvent composition for selective removal of COS from a gas stream containing same, said composition comprising a) at least one polyalkylene glycol alkyl ether of the formula (I) or 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone or a mixture of N-formylmorpholine and N-acetylmorpholine Wherein R 1 is an alkyl group having from 1 to 6 carbon atoms; R 2 is hydrogen or an alkyl group having from 1 to 4 carbon atoms; Alk is an alkylene group, branched or unbranched, having from 2 to 4 carbon atoms, and n is from 1 to 10; and b) at least one alkanolamine compound of the formula (II) or at least one piperazine compound of formula (III) wherein R 3 is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R 4 OH group; R 4 is a branched or unbranched alkylene group having from 1 to 6 carbon atoms; R 5 , independently in each occurrence, is hydrogen or an hydroxyalkyl group having from 1 to 4 carbon atoms; and R 6 is hydrogen, an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms. R 1 O—(Alk-O) n —R 2   (I) R 3 NHR 4 OR 6   (II)

1. A process for selective removal of COS from a gas stream containing COS and CO 2 , said process comprising contacting the gas stream with a solvent composition comprising
 a) 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone; and 
 b) at least one alkanolamine compound of the formula
   R 3 NHR 4 OR 6  (II) 
 
  or at least one piperazine compound of formula 
 
       
         
           
           
               
               
           
         
          wherein R 3  is hydrogen, an alkyl group having from 1 to 6 carbon atoms, or the R 4 OH group; R 4  is a branched or unbranched alkylene group having from 1 to 6 carbon atoms; 
         R 5 , independently in each occurrence, is hydrogen or an hydroxyalkyl group having from 1 to 4 carbon atoms; and R 6  is hydrogen, an alkyl group having from 1 to 6 carbon atoms or an hydroxyalkyl group having from 1 to 4 carbon atoms. 
       
     
     
       2. The process of  claim 1  wherein component b) is an alkanolamine of formula II in which substituent R 3  is hydrogen. 
     
     
       3. The process of  claim 1  wherein component b) is at least one of monoethanolamine, diethanolamine, methylethanolamine, diisopropanolamine, and 2-(2-aminoethoxy) ethanol. 
     
     
       4. The process of  claim 3  wherein component b) is monoethanolamine. 
     
     
       5. The process of  claim 1  wherein component b) is a compound of formula III. 
     
     
       6. The process of  claim 1  wherein the solvent composition contains less than about 8.6 weight percent of water.